54/8 Mr. E. F. Teschemacher on various Substances 



21*0 parts of Ammonia. 

 55*50 ... Carbonic acid. 

 23-50 ... "Water. 



100-00 

 being nearly equivalent to 1 atom of ammonia, 2 atoms of 

 carbonic acid, and 2 atoms of water. 



Formula NH a + 2CO a + 2HO, 

 and is consequently a bicarbonate of ammonia. 



The third substance was found at Saldanha Bay on the 

 coast of Africa, imbedded in patches in the mass of guano. 

 It is found in distinct crystals with numerous modifications, 

 many of the planes possessing sufficient brilliancy to enable 

 me to measure the angles by the reflecting goniometer. I 

 have given the measurements of one crystal, from which it 

 appears the primary form is the right rhombic prism of 

 57° 30' and 122° 30' : it has a cleavage parallel to plane M*. 

 Upon analysis I find this substance to be composed of — 



14*30 parts of Ammonia. 

 17*00 ... Magnesia. 

 30*40 ... Phosphoric acid. 

 38*10 ... Water. 



99*80 



which is nearly equivalent, to 1 atom ammonia, 1 atom mag- 

 nesia, 1 atom phosphoric acid, 5 atoms water. 



Formula NH S , MgO, P0 5 + 5HO. 

 It is therefore the ammonio-magnesian phosphate. The spe- 

 cific gravity is 1'65, hardness 2; it falls to powder before the 

 blowpipe, giving off water and ammonia. It occurs white, 

 translucent, sometimes coloured brown by the guano; it rea- 

 dily dissolves in weak acids. 



This substance is clearly derived from the guano ; but 

 being insoluble in water, it must have been held in solution by 

 some of the organic acids of the guano, and deposited there- 

 from in large crystals, as they are found, but disseminated in 

 patches only of the guano, in various parts of the beds. 



This substance not having been found before in a native 

 state, but hitherto only known as one of the artificial pro- 

 ducts of the laboratory, must be considered as a new mineral 

 body; I therefore propose to give it the mineralogical name 

 of Guanite, this name being derived from the circumstances 

 and locality of its formation. 



The source from which the first two substances, namely, 

 the phosphate of ammonia and the bicarbonate of ammonia, 



* See the angular measurements subjoined. 



